An elevation is different. It shows the face of something, or perhaps more correct, the projection of an object/s to a plane. But my testing suggests it produces SECTIONS, not elevations.
Yes, you can use abbreviations in tables and figures. All abbreviations used in tables and figures should be defined in the table note or figure caption, respectively, even though the abbreviations will be also be defined in the text if they are used there.
The concept of significant figures (or digits) is a convention for expressing the accuracy of a measurement. When working with real-world data, it is crucial that every measured value be as accurate as possible. Attempts must be made to minimize uncertainty when expressing measurements.